<div class="left">
    <div class="panel-group" id="accordion">
        <div class="panel panel-default">
            <div class="panel-heading">
                <h4 class="panel-title">
                    <a href="/admin/index.php">
                        主页
                    </a>
                </h4>
            </div>
        </div>
        <div class="panel panel-default">
            <div class="panel-heading">
                <h4 class="panel-title">
                    <a data-toggle="collapse" data-parent="#accordion"
                       href="#collapseTwo">
                        用户管理
                    </a>
                </h4>
            </div>
            <div id="collapseTwo" class="panel-collapse collapse">
                <ul class="list-group">
                    <li class="list-group-item"><a href="/admin/user_list.php">用户列表</a></li>
                </ul>
            </div>
        </div>
        <div class="panel panel-default">
            <div class="panel-heading">
                <h4 class="panel-title">
                    <a data-toggle="collapse" data-parent="#accordion"
                       href="#collapseTwo">
                        文章管理
                    </a>
                </h4>
            </div>
            <div id="collapseTwo" class="panel-collapse collapse">
                <ul class="list-group">
                    <li class="list-group-item"><a href="#">免费域名注册</a></li>
                    <li class="list-group-item">免费 Window 空间托管</li>
                </ul>
            </div>
        </div>
        <div class="panel panel-default">
            <div class="panel-heading">
                <h4 class="panel-title">
                    <a data-toggle="collapse" data-parent="#accordion"
                       href="#collapseTwo">
                        系统设置
                    </a>
                </h4>
            </div>
            <div id="collapseTwo" class="panel-collapse collapse">
                <ul class="list-group">
                    <li class="list-group-item"><a href="#">免费域名注册</a></li>
                    <li class="list-group-item">免费 Window 空间托管</li>
                </ul>
            </div>
        </div>


    </div>
</div>